Federal investigators discovered nude photos of underage girls at Jeffrey Epstein’s Manhattan townhouse, prosecutors allege.

CNN reports that prosecutors revealed the allegations in court on Monday, the same day that prosecutors an indictment against the 66-year-old hedge fund billionaire, who is being charged with operating a sex trafficking ring.

Epstein “has continued to maintain a vast trove of lewd photographs of young-looking women or girls in his Manhattan mansion,” prosecutors reportedly said, claiming that investigators found “at least hundreds—and perhaps thousands—of sexually suggestive photographs of fully- or partially nude females”

“Some of the nude or partially-nude photographs appear to be of underage girls, including at least one girl who, according to her counsel, was underage at the time the relevant photographs were taken.”

Epstein was arrested on Saturday and is reportedly being viewed as a flight risk.

According to CNN, prosecutors requested in a letter to the court that Epstein be ordered to remain in custody pending trial, characterizing him as “an extraordinary risk of flight.”

“If allowed to remain out on bail, the defendant could attempt to pressure and intimidate witnesses and potential witnesses in this case, including victims and their families, and otherwise attempt to obstruct justice,” the letter reportedly continued.

Epstein is expected to appear in court on Monday for a bail hearing.